Exothermic inserts for hot tops



Dec. 8, 1964 c. R. FUNK ETAL 3,159,887

EXOTHERMIC INSERTS FOR HOT TOPS Filed Jan. 31, 1963 2 Sheets-Sheet lINVENTORS ATTORNEYS United States Patent 3,15%,887 EXGTHERli HC ENSERTSFOR HGT TF Charles Robert Funlr, Westchester, and Eonaid K.

Matthews, Coatesrille, Pa, assignors to Lukens Steel Company,Coatesviile, Pa, a corporation of Pennsylvania Filed Jan. 31, 3363, er.No. 255,335 6 Claims. (Cl. 22-147) This invention relates to the art ofhot topping metal ingots and castings. More particularly it relates to ahot top structure which includes inserts made of exothermic material;the hot tops and exothermic inserts being so designed and correlated tofunction efficiently at less cost than present designs.

The steel-making industry has for many years used hot tops on its moldsfor ingots. Hot tops comprise removable extensions of the mold and wheningots are poured, the hot tops hold the upper portion of the moltensteel which subsequently reducts in volume as the steel cools andproduces within the hot top a shrinkage cavity. The steel whichsolidifies inside the hot top is subsequently severed from the ingotinasmuch as it is not commercially usable due to its shape, porosity,impurities, and is therefore discarded. With conventional steel ingotpractices, wherein exothermic heating in the hot top is not employecLthemetal discarded around the shrinkage cavity may amount to as high as 24%by volume of the metal in the entire ingot and usually amounts to 13-17%of the volume of the ingot, depending upon the ingot size and the gradeof steel. This percentage of volume is considered excessive and awell-known means of reducing same is by the employment of exothermicmaterial in the hot tops. Patent No. 2,390,500, to Walter M. Charman etal., of December 11, 1945, and Patent No. 2,841,843, to Nouveau, of July8, 1958, refer to methods of using exothermic material in ingot molds.

The use of exothermic material in the hot top reduces the volume whichhas to be discarded from the ingot to e 10% more or less of the weight,in that additional heat is added through the exothermic reactions tokeep the metal in the hot top molten, and the shrinkage cavity formed isthus less conical in shape with a corresponding reduction in the volumeof metal surrounding the shrink age cavity.

The most common method of using exothermic material in hot tops is theemployment of exothermic boards to line the inner face of the mold. Thisrequires special and expensive assembling and holding means to hold samein position. Moreover, these boards are placed below the top of the moldso that the mold wall acts as a back support which in turn reduces theusable portion of the mold. I

Solutions have been proposed which involve the use of exothermicmaterial as auxiliary lining both on the inside and the outside of thehot top structures. Also,

tiles or the like with exothermic 'mserts have been sug- V gested aslining for hot tops. However, the present practices and suggestedworkable solutionsall have the disadvantagethat the resultant hot top istoo expensive for making simple carbon and simple alloy steels. Theincreased good steel yield in such steel grades generally does notjustify the added expense of such known hot is provided with recessesfor specialty designed'exothern'iic inserts which can bestrategicallylooatedto:

ilhhfih? Patented Dec. 8}, 1954 (3) Permit a design which can be used onthe mold,-

partly within the mold, or all the way within the mold;

(4) Reduce the amount of exothermic material required with increasedeconomy; V

(5 Reduce the frequency of breakage where exothermic boards are used;

(6) Insure a more positive control of the exothermic reactions;

(7) Shorten the height of the standard hot top;

( 8) Decrease the volume of hot top metal;

(9) Retain hot top height for better metal feeding into ingot which isnot realized with exothermic side boards placed in the top portion; and

(l0) Retain hot top height for ease of stripping.

The primary object of this invention is provision of a hot topstructure. with exothermic inserts designed to function within the hottop to provide the above advantages and to be sufiiciently inexpensiveso that substantial savings are possible in the production of the lessexpensive grades of steel.

Other objects and features of novelty will appear as we proceed with thedescription of the embodiments of the invention which, for the purposesof the present p plication,- have been illustrated in the accompanyingdrawings, in which: 1 V

FlGURE 1 is a vertical sectional view through the upper portion of aningot mold with a'hot top resting thereon which includes exothermicinserts in accordance with the present invention;

FIGURE 2 is a plan view of the hot top shown in FIGURE 1;

FIGURE 3 is a plan view of the hot top showing more than one insert perside including several modified types 7 of inserts;

FIGURE 4 shows a round hot top with exothermic inserts located aroundthe diameter;

FIGURE 5 shows a plan view of an elongated rectangular shaped hot topwith the exothermic inserts in' FIGURE 9 is a perspective view of anexothermic in sert such as fits into a round hot top as shown in FIG-URE 4; 7

FIGURE 10 is a perspective view of an exothermic insert which is taperedfrom its bottom;

.FIGURE 11 is a perspective view of an exothermic insert having a fiat Tcross-section;

- FIGURE 12 is a perspective View of an exothermic, insert similar tothat shown in FIGURE 11 but tapered from thebottom upwardly; and

FIGURE 13 is a perspective view of an exothermic insert'havingserrations in its upper portion.

The exact location, width and number of inserts used will vary from shopto shop according to the end use of the product, the grades of steelproduced, and the mold design. It will be appreciated that varying the,number, size and location of inserts does not affect the scope oftheinvention. insofar as these matters will be within the knowledge of oneskilled in the art.

: Referring now to FIGURE 1, a hot top 10 which may be made ofconcreteor clay rests on the upper edge of 1 the ingot mold'lZ. The hop top 10carries around its 4. periphery a number of lugs 14 for handling the hottop y and providing a base for resting same on- .theingot mold Ireaction in the lower portion of the hot top as the steel is drawn intothe lower portion of the hot top by the solidifying of steel in theingot 12.

In FIGURE 2 it will be noted that the inserts 16 are received in grooveswhich flare or taper inwardly. Thus, the inserts 16 are secured insofaras lateral movement is concerned. Securing means such as angle plates 18which are nailed or otherwise secured to the lower portion of the hottop 10 beneath the inserts 16 serve to maintain the inserts 16 inposition and from sliding downward due to gravity. Similar plates 19 aresecured by nails or other appropriate means over the inserts to retardany tendency of the inserts to rise due to buoyancy when the moltensteel is contained in the hot top. 7

Whereas FIGURE 2 shows the employment of only one insert 16 on each ofthe four inner sides of the hot top, FIGURE 3 shows a pair of insertscarried within the hot top 20 on each inner side. For the purposes ofillustration only, each of the eight inserts shown in FIG- URE 3 aredifferent. As a general rule, however, the insertsare either all thesame, or only two or rarely three different types are employed,depending upon the desired result Inserts 22 and 24 are parallelepipedswith rectangular sides, being roughly in the shape of a board. Theinsert 22 is -flush with the hot top 20 and is held in place with flatbar retainers 26 which are nailed or otherwise secured to the hot top 20along the sides of the insert 22. Plates (not shown) similar to angleplates 18 may be placed at the bottoms of the inserts and plates 21 aresecured on the top to prevent vertical movement. Insert 24 is secured tothe 'hot top 20 in a manner similar to that of insert 22 except that theretainers 28 are offset to accommodate the extension of the insert 24beyond the inner face of the hot top 10. The advantages of the inserts22 and 24 reside in their practicality of use. They may be prepared inconvenient standard sizes and cut to the particular lengths desired forthe hot top involved.

The inserts 30 and 32'are trapezoidal in cross-section, but thecross-section is uniform throughout the length of the inserts incontrast to the inserts 16 shown in FIGURE 1. The interlocking fit ofthe inserts Siland 32 with the hot top 20 prevents all movement exceptvertical movement which is prevented by angle plates (not shown) such asangle plates 18in FIGURE 1 and plates 21 on the top. vInsert 30 extendsoutwardly from the inner surface of the hot top 20 whereas insert 32 isflush with such surface. Accordingly, in the initial stages of theinserts reaction, insert 30 will have more surface exposed to the moltenmetal than insert 32. The more surface exposed by insert 30 produces agreater heat trans- Eerence to the molten metal from the exothermicreac-. tion in insert 30 during its initial stages of reaction, whereasinsert 32 reacts more nearly uniformly until the, insert is spent. Thesame distinction, of course, exists between inserts 22 and 24; FIGURE 6shows an insert such as inserts 22 and 24 whereas FIGURE 7 shows aninsert such as inserts 30 and 32.

Inserts 34 and 36 have a more positive tongue-andgroove interlock withthe hot top 20 than is the case with inserts30 and 32. A perspectiveview of insert 34 is shown in FIGURE 11 which, it will be noted, has anul Eorm T-shaped cross-section.

It will be noted that insert 38 shown in FIGURE 12 also has a Tcross-section. However, unlike insert 34, it is tapered towards the topand need only be secured to the hot top at its lower aspect. In asimilar manner, insertf31 has-1a.trapezoidal.cross-section which taperstowards the top and thus need only be secured in its lower aspect. Theincreased area which is exposed in the lower aspect in each of thesemodifications provides an increased heat generating area which, in turn,tends to level the bottom of the sink-hole of the cooling metal in thehot top and decreases the amount of metal which must be removed.However, inserts 31 and 38 must, in effect, be custom made and cannot beproduced in long lengths such as inserts 22, 24, 30, 32, 34, and 36,which can be cut to the desired lengths like boards.

Inserts 46 and 42 have upright T-shapes as shown in FIGURE 8. This shapeis af value where, because of the size of the hot top, the shrinkagecavity is expected to be concentrated in the upper portion of the hottop. If desired, and the hot top is so adapted, this insert may be usedwith the head of the T inverted ,to produce an increased heat generatingarea in the lower position of the hot top for the opposite effect. arenormally secured in place by securing means as illustrated for inserts22 and 24, which need, obviously, only to be placed at the head of theT.

The hot tops may sometimes be cylindrical in configuration such as hottop 44 shown in plan View in FIG- URE 4. In such event, curved inserts46 and 48 as shown in FIGURE 9 are fitted in the recesses provided inthe hot top. it will be appreciated that such inserts 46 and 48 arecurved versions of inserts such as 22 and 24 heretofore descnibed inFIGURE 3. The straight sides of inserts 46 and 48 are directed towardsthe central longitudinal axis of hot top 40 and consequently the inserts46 and 48 are held in place by a tongue and groove arrangement and needonly be secured against vertical displacement due to gravity or theirbuoyancy in the molten metal by plates 47 on the top and similar means(not shown) on the bottom of the insert. FIGURE 5 shows an elongated hottop 50 with two inserts 52 which are similar to insert 30 shown in FIG-URE 3, but have a greater width. This modification is illustrated toshow the adaptability of the invention to many configurations of hottops.

FIGURE 13 shows insert 54 which is of special interest. The insert 54 isthus fluted in its upper aspect with tapered channels 56 which diminishas they extend downwardly and finally terminate in the lower aspect ofthe insert 54. After molten metal comes into contact with this insert,the increased area in the upper portion provides an increased generationof heat to the metal in the vicinity thereof. However, as the level ofthe metal lowers due to shrinkage in'the mold, the upper portion will bemore quicklyspentwhereas the lower portion with less area in contactwith the molten metal and more exothermic material will tend to generateheat for a longer period of time to the metal in its vicinity. Thisdesign permits an efficient use of exothermic material with a minimalwaste ofmetal along the sides of the sink-hole.

The foregoing detailed description of. the invention and variousmodifications thereof has been given for clearness 'of understandingonly, and no unnecessary limitations should be understood therefrom, forfurther modifications will be obvious to those skilled in the art.

' zoidal.

3. A combination as set forth in claim 1 wherein said Inserts 40 and 425 cross-sectional shape of said longitudinal groove is in the form of aflat T. I

4. A hot top in combination with an ingot mold con taining molten metal,said hot top having a longitudinal groove in theinner face thereof, saidlongitudinal groove being Wider at the bottom than the top portion, andan insert of exothermic material of a shape corresponding to said groovekeyed Within and interlocked with said groove, the outer face of saidinsert substantially immersed in said molten metal.

5. A hot top in combination With an ingot mold containing molten metal,said hot top having a recessed portion in the inner face thereof, saidrecess being T-shaped, and an insert of exothermic materialcorresponding in shape to said recess keyed within and interlocked withsaid recess, one side of said insert substantially immersed in saidmolten metal.

6. The invention of claim 1 wherein the exothermic insert for a hot topis fluted in its upper portion. 5 I

References Cited by the Examiner UNITED STATES PATENTS MICHAEL V. BRINDISI, Primary Examiner.

1. A HOT TOP OF CLAY, CEMENT, OR THE LIKE, IN COMBINATION WITH AN INGOTMOLD HAVING MOLTEN METAL THEREIN, SAID HOT TOP INCLUDING A VERTICALLONGITUDINAL GROOVE OF UNIFORM CROSS-SECTION IN THE INNER FACE THEREOF,AND AN INSERT OF EXOTHERMIC MATERIAL OF UNIFORM CROSS-SECTIONCORRESPONDING TO THE AFORESAID CROSS-SECTION OF SAID LONGITUDINAL GROOVEKEYED WITHIN AND INTERLOCKED WITH SAID GROOVE, ONE SIDE OF SAID INSERTSUBSTANTIALLY IMMERSED IN SAID MOLTEN METAL.